1. Field of the Invention
The present invention relates to an element substrate, printhead, and printing apparatus.
2. Description of the Related Art
There is known an element substrate (driving head) including a plurality of driving elements for generating thermal, mechanical, magnetic, or light (electromagnetic wave) energy. The element substrate sometimes needs to directly or indirectly inspect a phenomenon generated upon driving and feed it back to the driving control.
For example, a case in which such an element substrate is applied to an inkjet printhead (to be referred to as a printhead hereinafter) will be examined. In the printhead, all or some nozzles may generate a discharge failure owing to clogging of nozzles with a foreign substance, bubbles entering an ink supply path, a change of wettability of the nozzle surface, or the like. In this case, nozzles suffering a discharge failure as a phenomenon generated upon driving need to be specified and reflected in image supplement and printhead recovery work.
To implement this technique, Japanese Patent Laid-Open No. 2008-023987 discloses a method in which a temperature detection element formed from a thin-film resistor is arranged on an insulating film in each printing element for performing electrothermal conversion. The temperature detection element detects temperature data of each nozzle to inspect a nozzle suffering a discharge failure based on a temperature change.
When detection elements and an accessory circuit are arranged near respective driving elements, it is necessary not to affect the structure including the driving elements, the function, and the performance. In addition, the arrangement location is restricted.
For example, when a temperature detection circuit is arranged in the printhead disclosed in Japanese Patent Laid-Open No. 2008-023987, it is necessary not to change the printing element, its wiring, the ink supply path, and the nozzle structure.